... you very much. Non Errosion ETC Tube Solar Water HeatersAccessories: Optional1) Assistant tank: 3L, 5L,12L,40L, 60L or equal ... water into solar tank at first time, if the solar tank is full, the assistant tank will controll to stop into water. When the water in tank ... drop down, and cold water will into assistant tank again 2) Magnesium rod: Soften water, protection solar tank 3) Electric heater: ...